| With the characteristics of high mechanical strength,physical barrier,ultra-light and ultra-thin single-layer structure,etc.,graphene is often used as a protective layer for anti-corrosion.However,the graphene protective layer will fail due to its high electrical conductivity,and possible presence of defects and grain boundary structure.The principle of existing improvements for graphene anti-corrosion protective layer mainly include using more complicated device to repair defects,or inhibiting the conductivity of the graphene protective layer,which is not suitable for the protection of conductive devices.This thesis is devoted to developing a simple and feasible anti-corrosion methodology for conductive devices.The anti-corrosion performances of different types of protective layers are compared,the preparation process of the protective layer is optimized and the mechanism related to the corrosion process is studied.The specific work is as follows:(1)Based on a simple multiple-time dip coating self-assembly method,utilizing the electrostatic adsorption between ?-mercaptoethylamine and sulfonated graphene,and the covalent cross-linking reaction between the functionalized graphene oxide sheets modified with mercapto/amino groups,different types of graphene protective layers are prepared on the surface of copper foil.Under the condition of 4-time dipping and single dipping time of 30 s for the two types of self-assembled protective layers,the polarization current and the oxidation current of the amino-functionalized graphene oxide protective layer are lower.When the amino-functionalized protective layer dipped 16 times,the corrosion electrochemical parameters of this type of protective layer are the lowest.The potentiostatic polarization current polarization current at 0.2 V is 0.2?0.5 mA/cm2,and the maximum oxidation current is 3.4 mA/cm2.The corrosion current reaches the order of 10-7 mA/cm2.(2)Based on amino-modified functionalized graphene oxide covalent cross-linking reaction,the effect of various dipping factors on the corrosion resistance of graphene protective layer is systematically investigated.As the dipping period per time increases,the optimized APTES concentration increases accordingly.The anti-corrosion performance of the protective layers obtained by multiple-time dip coating.These protective layers are related to different dipping periods per time and corresponding optimized concentrations.And the appropriate APTES concentration is selected.The dipping times(2 times)and the optimized concentration of APTES(32 mg/mL)are fixed,the optimized dipping period per time is 20 min,and the dipping temperature is 50?.Finally,hydrazine is used as the reducing agent to prepare rGO@APTES solution.The potentiostatic polarization current at 0.2 V of the protective layer prepared by this solution is lower than 0.5 mA/cm2,and the potentiostatic polarization current at 0.8 V drops to 4 mA/cm2.The maximum conductivity of this type of protective layer is 166 S/cm.(3)The above electrochemical corrosion process involves the electro-oxidation reaction in the micro area of the metal surface.It is necessary to understand the electrochemical reaction process in the micro area and the principle of charge transfer.Therefore,we have developed an optical detection method for a single nanoparticle based on dark field microscopy,which converts the electrical signal on the surface of a single PtTe nanorod caused by electrooxidation of formic acid into a scattering light signal.The detect limit of this detection method can reach 0.0396 fA.Through this method,the instantaneous current curve,the electrochemical oscillation modes and highly active site distribution of a single PtTe nanorod can be obtained.Then the structure-effect relationship between the microstructure of the metal and the electrooxidation activity can be established.This study benefits to deepen the understanding of the electrochemical corrosion process and charge transfer in micro areas of the metal surface. |
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